Real-time communication systems include communication systems that guarantee delivery of communication message data within predetermined time limits. Real-time communication systems are used in a wide range of applications, with industrial control systems being one example where real-time communications are important to the successful operation of manufacturing, control, automation, and other industrial processes.
Many existing real-time industrial applications use wired communication and specialized protocols to achieve latency and reliability. Wired solutions are, however, expensive and error prone as wired cables are susceptible to electromagnetic interference from the high voltage currents used to drive industrial devices. The wired networks can include several hundred devices controlled by single/multiple controllers. Further, faulty cabling often results in errors that incur costs due to lost productivity and increased maintenance requirements.
Wireless solutions have the advantage of cleaner and easier installation. Wireless solutions that operate in the 1 GHz or greater range have reduced susceptibility to electromagnetic interference from most industrial equipment. However, existing wireless communication systems are not suitable for the real-time operational requirements of industrial applications that include real-time communication requirements between multiple devices. For example, existing orthogonal frequency division multiplexing (OFDM) systems employed in standard wireless technologies, such as 802.11g/n, cannot support the strict latency and reliability requirements, although some existing protocols support relaxed soft-real-time requirements using enhancements such as an extension for Quality of Service (QoS) with 802.11e and other medium access protocols. Additionally, OFDM and code division multiple access (CDMA) techniques that are used with cellular data networks are typically unsuitable for use in industrial automation systems due to increased protocol complexity and equipment cost. Consequently, improved systems and methods for wireless communication that enable real-time operation would be beneficial.